Abstract
This paper describes and analyzes the phenomena that occur in the case of a current interruption due to faults in the high voltage circuit breaker. That happens during connection of a generator to the network without meeting the synchronization conditions. This paper also describes and analyzes the important factors that have to be considered during the specification of SF6 circuit breakers for high voltage generators. A high direct current component in the fault current poses a major problem during such interruptions. To investigate this problem and propose possible solutions, simulations were performed on a power network model completed with the network’s data, using software such as EMTP-ATP, PSS-E and MATLAB. Various modes of operation were simulated, which are important for analyzing the strain on circuit breakers near the generator. Based on the performed simulations, it can be concluded that circuit breakers with rapid reactions in interrupting the fault current in an energy system are not always a favorable solution due to the high value of the direct current component in the fault current, which prevents the current from passing through zero within a short time.